Larval Mortality Research Articles

Screening of volatile compounds of essential oils with acaricidal activity in Rhipicephalus microplus larvae using a new in vitro evaluation method

ABSTRACT The study assessed the acaricidal properties of 20 compounds derived from essential oils against the Rhipicephalus microplus tick, a significant menace to tropical livestock with considerable economic losses. A novel methodology was devised, involving the determination of mortality times for R. microplus larvae upon direct contact with these compounds. Mortality times were compared against a negative control (soybean oil) and two positive controls (commercial pour-on products). Tests were conducted in 48-well polyethylene plates, with around 100 larvae immersed in 200 µl of oil (at a 100% dose). The 10 compounds exhibiting the shortest mortality times were subsequently diluted in soybean oil at varying concentrations. Notably, thymol exhibited potent acaricidal activity, with the lowest effective dose (1.56%) resulting in larval mortality within 15 minutes, whereas positive controls necessitated over 66 minutes. A correlation was established between the molecular structure of the compounds and their acaricidal efficacy, indicating that cyclic compounds containing 10 carbon atoms demonstrated heightened lethality compared to acyclic counterparts. This innovative methodology enables the rapid identification of substances with substantial acaricidal potential in vitro, yielding results within minutes, in stark contrast to the traditional larval immersion test, which demands a minimum of 24 hours for conclusive outcomes.

The Effect of Soursop and Betel Leaf Extracts as Organic Pesticides in Pest Control of Spodoptera exigua (Lepidoptera: Noctuidiae) on Onion (Alium ascalonicum L.) Cultivation

Spodoptera exigua is a major pest in onion cultivation. S.exigua larvae have a rapid spread and can cause yield losses of up to 20-100% if not controlled. Soursop leaf extract and betel leaf pesticides can cause mortality in S.exigua pests. This is due to secondary metabolites found in soursop leaf extract and betel leaf such as acetogenin, alkaloids, flavonoids, terpenoids, steroids, saponins and tannins. The purpose of this study was to determine the effectiveness of soursop leaf extract and betel leaf and the combination of both in controlling S.exigua pests. This study used a non-factorial Complete Randomized Design method with 7 treatments, namely P0 = Control, P1 = 30% soursop leaf extract, P2 = 60% soursop leaf extract, P3 = 30% betel leaf extract, P4 = 60% betel leaf extract, P5 = 15% soursop leaf extract + 15% betel leaf extract, P6 = 30% soursop leaf extract + 30% betel leaf extract. The results showed that the P2 treatment had the highest mortality rate with 67.50% mortality and the P3 treatment had the lowest mortality rate of 25.00%. Symptoms of attack show that the larvae are initially actively eating and then begin to stay away from feed, the larvae then show a change in color to brown and slowly remain still and die. The duration of pest mortality showed the fastest mortality occurred in 24 hours with the death of 20 larvae, larval mortality continued to increase with each observation. Testing on natural enemies showed results that the use of soursop leaf extract did not show any death

Effectiveness of Biopesticides Nicotiana tabacum L and Ageratum conyzoides L As Controlling Spodoptera exigua in Red Onion (Allium ascalonicum L.)

Shallots (Allium ascalonicum) are a commodity in Indonesia that has high economic value. One of the pests that often attacks and reduces shallot yields is the onion caterpillar pest S. exigua. Tobacco plants and babadotan weeds are types of plants that can be used as botanical pesticides as a method of controlling and preventing pest attacks on plants. Tobacco and babadotan plants contain secondary metabolite compounds such as alkaloids, flavonoids, saponins, terpenoids and tannins which are able to kill insect pests on shallot plants. The aim of this research is to determine the effectiveness of tobacco extract (Nicotiana tabacum L.) and Babadotan (Ageratum conyzoides L.) as control of the onion caterpillar pest Spodoptera exigua on shallots. The highest combined mortality rate was treated with T6 at 96JSP with an average of 75%,The lowest larval mortality percentage test was found in T2 with an average mortality result of 22.50%.The results of biosafety testing show that the combination of tobacco extract and babadotan extract cannot be used together. From the conclusions that have been obtained, the extracts of (Nicotiana tabacum L.) and (Ageratum conyzoides L.), both single extracts and combination extracts, are effective in controlling the pest S.exigua

Integrated Pest Management Precision: Harnessing the Joint Influence of Entomopathogenic Fungi, Nematodes, and Chlorantraniliprole for Targeted Control of Fall Armyworm (Spodoptera Frugiperda)

Background: The Spodoptera frugiperda, commonly known as the fall armyworm (FAW), is a significant pest impacting agricultural productivity worldwide. Originating from tropical and subtropical regions, FAW has shown a high capacity for migration and destruction across a wide variety of crops. Integrated Pest Management (IPM) strategies offer sustainable approaches to managing pest populations, minimizing environmental impact, and reducing reliance on chemical insecticides. Objective: This study aimed to evaluate the efficacy of combining biological control agents, specifically Heterorhabditis bacteriophora (Hb) and Beauveria bassiana (Bb), with the chemical insecticide chlorantraniliprole (Ch) against third and fifth instar larvae of S. frugiperda. The study sought to determine the potential synergistic effects of these combinations on larval mortality and developmental disruption. Methods: The research encompassed laboratory bioassays, greenhouse, and field trials to assess the impact of the biocontrol agents and chlorantraniliprole, both individually and in combination, on FAW larval mortality and development. Larval populations of S. frugiperda were collected and reared under controlled conditions. Treatments applied included Hb, Bb, Ch, Hb+Bb, Hb+Ch, Bb+Ch, and Hb+Bb+Ch. Mortality rates were recorded at 3, 5, and 7 days post-treatment, while developmental parameters were assessed through pupation rates, adult emergence, and egg eclosion percentages. Results: The combined application of Hb, Bb, and Ch significantly increased mortality rates in both the third and fifth instar larvae compared to individual treatments, with the highest mortality observed in the Hb+Bb+Ch group (100% by day 7). Developmental disruptions were also noted, including reduced pupation rates, adult emergence, and egg eclosion, particularly in treatments involving the combined use of biocontrol agents and chlorantraniliprole. Statistical analysis confirmed the significance of these findings (P<0.01). Conclusion: The integration of Hb, Bb, and Ch presents a viable IPM strategy for effectively managing S. frugiperda populations. This combination not only enhances larval mortality but also disrupts developmental stages, offering a potential reduction in FAW infestation levels and associated crop damages. These results underscore the importance of adopting sustainable pest management practices that leverage synergistic effects between biological and chemical agents.

Larvicidal activity of Acacia nilotica extracts against Culex pipiens and their suggested mode of action by molecular simulation docking

Mosquitoes are one of the deadliest and most hazardous animals on Earth, where they transmit several diseases that kill millions of people annually. There is an ongoing search almost everywhere in the world for more effective and contemporary ways to control mosquitoes other than pesticides. Phytochemicals are affordable, biodegradable biological agents that specialize in eliminating pests that represent a risk to public health. The effectiveness of Acacia nilotica methanol and aqueous leaf extracts against 4th instar larvae was evaluated. The results revealed that the methanol extract of A. nilotica had a noticeable influence on the mortality rate of mosquito larvae, especially at high concentrations. Not only did the mortality rate rise significantly, but the hatching of the mosquito eggs was potentially suppressed.Terpenes, fatty acids, esters, glycosides, pyrrolidine alkane, piperazine, and phenols were the most prevalent components in the methanol extract, while the aqueous extract of A. nilotica exclusively showed the presence of fatty acids. The insecticidal susceptibility tests of both aqueous and alcoholic extract of A. nilotica confirmed that the Acacia plant could serves as a secure and efficient substitute for chemical pesticides because of its promising effect on killing larvae and egg hatching delaying addition to their safety as one of the natural pesticides. Molecular docking study was performed using one of the crucial and life-controlling protein targets, fatty acid binding protein (FABP) and the most active ingredients as testing ligands to describe their binding ability. Most of the structurally related compounds to the co-crystallized ligand, OLA, like hexadecanoic acid furnished high binding affinity to the target protein with very strong and stable intermolecular hydrogen bonding and this is quite similar to OLA itself. Some other structural non-related compounds revealed extraordinarily strong binding abilities like Methoxy phenyl piperazine. Most of the binding reactivities of the majortested structures are due to high structure similarity between the positive control, OLA, and tested compounds. Such structure similarity reinforced with the binding abilities of some detected compounds in the A. nilotica extract could present a reasonable interpretation for its insecticidal activity via deactivating the FABP protein. The FABP4 enzyme inhibition activity was assessed for of both methanolic and aqueous of acacia plant extract and the inhibition results of methanol extract depicted noticeable potency if compared to orlistat, with half-maximal inhibitory concentration (IC50) of 0.681, and 0.535 µg/ml, respectively.

Lessons from the calibration and sensitivity analysis of a fish larval transport model

Numerous fish populations show strong year-to-year variations in recruitment. The early life stages play a crucial role in determining recruitment and dispersal patterns. A helpful tool to understand recruitment and dispersal involves simulations with a Lagrangian transport model, which results from the coupling between a hydrodynamic model and an individual-based model. Larval transport models require sound knowledge of the biological processes governing larval dispersal, and they may be highly sensitive to the parameters selected. Various assumptions about larval traits, behaviour and other model parameters can be tested by comparing simulation results with field data to identify the most sensitive parameters and to improve model calibration. This study shows that biological parameterization is more important than inter-annual variability in explaining the year-to-year differences in larval recruitment of common sole in the North Sea and the eastern English Channel. In contrast, year-to-year variability of connectivity leads to higher variability than changes in the biological parameters. The most influential parameters are pelagic larval duration, spawning period and mortality. Calibration over a 12 yr recruitment survey shows that a scenario with low mortality associated with a long larval duration and behaviour involving nycthemeral and tidal migration best reproduces the observations. This research provides insights into factors influencing fish dispersal and recruitment, suggesting a strategy for enhancing the accuracy of models in upcoming studies. The study supports the improvement of larval dispersal modelling by incorporating an easily applicable sensitivity analysis for both calibration and validation. Incorporating sensitivity analyses enhances larval dispersal models, providing performing tools that can contribute to informed fisheries management and understanding of recruitment variability.

Production and characterization of Trichoderma asperellum chitinases and their use in synergy with Bacillus thuringiensis for lepidopteran control.

Despite their known negative effects on ecosystems and human health, synthetic pesticides are still largely used to control crop insect pests. Currently, the biopesticide market for insect biocontrol mainly relies on the entomopathogenic bacterium Bacillus thuringiensis (Bt). New biocontrol tools for crop protection might derive from fungi, in particular from Trichoderma spp., which are known producers of chitinases and other bioactive compounds able to negatively affect insect survival. In this study, we first developed an environmentally sustainable production process for obtaining chitinases from Trichoderma asperellum ICC012. Then, we investigated the biological effects of this chitinase preparation - alone or in combination with a Bt-based product - when orally administered to two lepidopteran species. Our results demonstrate that T. asperellum efficiently produces a multi-enzymatic cocktail able to alter the chitin microfibril network of the insect peritrophic matrix, resulting in delayed development and larval death. The co-administration of T. asperellum chitinases and sublethal concentrations of Bt toxins increased larval mortality. This synergistic effect was likely due to the higher amount of Bt toxins that passed the damaged peritrophic matrix and reached the target receptors on the midgut cells of chitinase-treated insects. Our findings may contribute to the development of an integrated pest management technology based on fungal chitinases that increase the efficacy of Bt-based products, mitigating the risk of Bt-resistance development. © 2024 Society of Chemical Industry.

Laboratory Bioassays to Study the Efficacy of Diamides against Leucinodes orbonalis (Guenee) of Brinjal

This study was undertaken with the objectives to investigate the toxicity of insecticides against larval stage of L. orbonalis in the laboratory. Management stratagies of the pest requires frequent spraying of chemical insecticides. Due to continuous spraying of insecticides L. orbonalis had developed a resistance to different insecticides that are urgently needed to test new molecules. In this bioassay, seven insecticides such as Cyantraniliprole 10OD, chlorantraniliprole 18.5SC, flubendiamide 480SC thiodicarb 75WP, methomyl 40SP, cartap hydrochloride and profenophos 50EC belonging to different insecticides groups were tested against L. orbonalis in the laboratory. In this bioassay larval mortality showed increasing trend with maximum percent mortality observed at 72HAT. All the treatments were found significantly superior over UTC. Among the seven insecticides tested against L. orbonalis, three diamides were found to be significantly superior. Cyantraniliprole 10OD recorded significantly highest percent larval mortality (97.26%), followed by chlorantraniliprole 18.5SC (94.14%) flubendiamide 480SC (88.45%), thiodicarb 75WP (77.53%), methomyl 40SP (71.50%), cartap hydrochloride 50SP (68.04%) and profenophos 50EC (65.88%). It is suggested that diamides may be used for the control of L. orbonalis.

Efficacy of Entomopathogenic Staphylococcus Bacteria as a Biocontrol Agent against Rhipicephalus microplus Ticks: Assessing Reproductive Inhibition and Mortality Rates.

Rhipicephalus microplus is a persistent ectoparasite of cattle that causes bovine anaplasmosis and babesiosis, causing economic losses worldwide. Chemical treatment is the primary method for tick control, but the emergence of pesticide-resistant ticks is a major challenge. Alternative biocontrol strategies utilizing entomopathogenic microorganisms are being explored. This study aimed to validate the species identification and assess the efficacy of four strains of Staphylococcus bacteria (S. shinii S1 and S-2, S. succinus, and S. xylosus) previously reported as being entomopathogenic to R. microplus ticks. According to the bioassays, S. shinii S-1 exhibited the greatest degree of reproductive inhibition (47%), followed by S. succinus (44.3%) at a concentration of 1 × 108 cfu/mL. S. xylosus displayed decreased reproductive inhibition (6.3%). In an additional bioassay, S. shinii S-1 exhibited a significant larval mortality of 67.63%, followed by S. succinus with 66.75%, S. shinni S-2 with 64.61%, and S. xylosus with 28.18% mortality. The common signs of infection observed on these ticks included swelling, yellowish exudate on the hypostome, and reduced limb mobility and color change, except for S. succinus, which did not cause color changes. These bacteria were naturally found on bovine skin. However, further studies are needed to confirm their potential as promising alternatives or complementary agents to existing acaricidal compounds.

A C-type lectin (CTL2) mediated both humoral and cellular immunity against bacterial infection in Tribolium castaneum

C-type lectins (CTLs) play essential roles in humoral and cellular immune responses of invertebrates. Previous studies have demonstrated the involvement of CTLs in the humoral immunity of Tribolium castaneum, a worldwide pest in stored products. However, the function of CTLs in cellular immunity remains unclear. Here, we identified a CTL gene located on chromosome X and designated it as CTL2 (TcCTL2) from T. castaneum. It encodes a protein of 305 amino acids with a secretion signal peptide and a carbohydrate-recognition domain. TcCTL2 was mainly expressed in the early pupae and primarily distributed in the hemocytes in the late larvae. It was significantly upregulated after larvae were infected with Escherichia coli or Staphylococcus aureus, while knockdown of TcCTL2 exacerbates larval mortality and bacterial colonization after infection. The purified recombinant TcCTL2 (rTcCTL2) can bind to pathogen-associated molecular patterns and microbes and promote hemocyte-mediated encapsulation, melanization and phagocytosis in vitro. rTcCTL2 also induced bacterial agglutination in a Ca2+-dependent manner. Knockdown of TcCTL2 drastically suppressed encapsulation, melanization, and phagocytosis. Furthermore, silencing of TcCTL2 followed by bacterial infection significantly decreased the expression of transcription factors in Toll and IMD pathways, antimicrobial peptides, and prophenoloxidases and phenoloxidase activity. These results unveiled that TcCTL2 mediates both humoral and cellular immunity to promote bacterial clearance and protect T. castaneum from infectious microbes, which will deepen the understanding of the interaction between CTLs and innate immunity in T. castaneum and permit the optimization of pest control strategies by a combination of RNAi technology and bacterial infection.

Ontogeny and tissue specific expression profiles of recombination activating genes (RAGs) during development in Nile tilapia, Oreochromisniloticus

Recombination activating genes (RAGs) mediates the process of rearrangement and somatic recombination (V(D)J) to generate different antibody repertoire. Studies on the expression pattern of adaptive immune genes during ontogenic development are crucial for the formulation of fish immunization strategy. In the present study, Nile tilapia was taken to explore the relative expression profile of RAG genes during their developmental stages. The developmental stages of Nile tilapia, i.e., unfertilized egg, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 and 30 days post-hatch (dph) and kidney, blood, gill, liver and spleen tissues from adult fish were collected and the cDNA synthesis was carried out. Gene specific primers for RAG-1 and RAG-2 of Nile tilapia were designed and their annealing temperature (Tm) was optimized by gradient PCR. Consequently, PCR was performed to confirm the specific amplification of RAG-1 and RAG-2 genes. Quantitative real-time PCR (qRT-PCR) gene expression of RAG-1 and RAG-2 were noticed in all the developmental stages; however, a significant increase was observed after 12 dph and peaked at 24 dph, followed by a gradual decrease until 30 dph. Tissue-specific gene expression profiling revealed that the highest expression of RAG-1 and RAG-2 was observed in the kidney, followed by spleen, gill, liver and blood. The findings of the study explored the suitable timing of lymphoid maturation that could be technically used for the adoption of strategies to improve disease resistance of fish larvae for mitigating larval mortality.

Larvicidal Activity of Some Aromatic Thiosemicarbazone and Metal Complexes [Ni (II), Cu (II), Co (II)] Against Aedes (Stegomyia) aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) (Diptera: Culicidae) Larvae.

A series of aromatic thiosemicarbazone-oxime [TP1 and TP2] derivatives and their Ni(II), Cu(II), and Co(II) complexes were synthesized, and their larvicidal activity was evaluated against Aedes aegypti and Aedes albopictus larvae. The efficacy of these substances to Aedes albopictus larvae has been demonstrated for the first time. Laboratory colonized Aedes aegypti and Aedes albopictus larvae were subjected to larvicidal activity tests. Larval mortality rates at 24 and 48 hours were recorded and LC50 values were calculated. The study was carried out at Aydın Adnan Menderes University in 2021. For Aedes aegypti, LC50 of TP1 and its Co(II) complex were 15.41, 9.75, μg/mL whereas for TP2 and its Co(II) complex, LC50 were 21.62, 20.50 μg/mL after 24 and 48 h respectively. For Aedes albopictus, TP1 and its Co(II) complex showed an LC50 of 12.06, 8.75 μg/mL, whereas TP2 and its Co(II) complex showed an LC50 of 32.87, 25.48 μg/mL, for 24, and 48 h respectively. Both TP1 and TP2 compounds and their Co(II) complexes presented high efficacy against the larvae; it can be said that C=S groups in thiosemicarbazone derivatives are effective in showing activity and for this reason, studies should be continued to make these components effective.

Biolarvicide activity of extract and essential oil of culantro (Eryngium foetidum L.) on Culex quinquefasciatus larvae in silico and in vitro


 
 
 
 Background: Filariasis, a priority tropical disease in Indonesia, is transmitted by the Culex quinquefasciatus mosquito. The use of conventional synthetic larvicides can lead to environmental and health issues, including poisoning and resistance in target insect populations.
 Objective: This study explores the utilization of biolarvicides derived from culantro (Eryngium foetidum) to mitigate these adverse efects, focusing on analyzing the components and evaluating the larvicidal eficacy of both the extract and essential oil of E. foetidum.
 Method: This study employed a molecular docking approach to examine in silico biolarvicidal activity against the odorant binding protein (OBP) receptor and conducted in vitro experiments on Cx. quinquefasciatus larvae using varying concentrations of E. foetidum extract (100, 250, and 500 ppm) and essential oil (10, 50, and 100 ppm).
 Results: The in silico study identified hynokiflavone and longifenaldehyde as the compounds with the most potent activity, demonstrating binding a inities of -10.2 and -9.5 kcal/mol, respectively. The in vitro assays revealed that the E. foetidum extract achieved 75% larval mortality at an LC50 of 78.59 ppm, while the essential oil resulted in 88% mortality with an LC50 of 10.13 ppm.
 Conclusion:The extract and essential oil of E. foetidum exhibit significant biolarvicidal activity against Culex quinquefasciatus, offering promising plant-based alternatives to traditional larvicides, with implications for safer and more sustainable vector control strategies.
 
 
 

Isolation of a Novel Pythium Species, P. thermoculicivorax, and Trichoderma sp. from Natural Enzootic Mosquito Larval Infections.

Only a handful of microbial mosquito larval pathogens have been described to date. Sampling several natural enzootic infections of mosquito larvae in southwestern Florida indicated the presence of microbial pathogens capable of extensive larval mortality. A microscopic analysis of one sample site revealed extensive apparent growth of a Pythium-like microbe on mosquito larvae, with the highest degree of infection observed in the siphon and head regions. Structures consistent with sporangia were seen on infected insects after lactophenol blue staining, and higher-resolution scanning electron microscopy (SEM) micrographs showed sporangia and encysted zoospores targeting the head and siphon regions. The isolate was single-colony purified, and molecular identification targeting the ITS and COX1 loci coupled to phylogenetic reconstruction indicated that the isolate belonged to the Pythium genus but was distinct from its closest characterized species, P. inflatum. Morphological features were characterized, with the isolate showing rapid growth on all mycological media tested and relatively high thermotolerance, capable of robust growth at 37 °C; hence, it was designated P. thermoculicivorax. Sampling from a second series of natural infections of mosquito larvae resulted in the molecular identification of three Trichoderma isolates, one with high similarity to T. strigosum and the other two clustering closely with T. asperellum. These data highlight the occurrence of natural enzootic infections of mosquito larvae, potentially as a resource for the identification of new mosquito pathogens.

Impact of nano- and micro-sized polystyrene beads on larval survival and growth of the Pacific oyster Crassostrea gigas

This study successionally monitored how nano- and micro-sized polystyrene beads (MNPs) influence larval mortality, growth, and attachment behavior of the Pacific oyster Crassostrea gigas related to MNP diameter and concentration. D-shaped larvae were sequentially exposed to three-diameter MNPs (0.55, 3.00, 6.00 µm) at five concentrations (0, 0.1, 1.0, 10, 20 μg/mL), and their mortality, growth stages and attachment were observed daily until they die. In addition, MNP intake and accumulation in larvae at each growth stage were determined using fluorescent beads. Deterioration in larval growth and survival was observed under all the exposure conditions, while significant negative effects on the growth parameters were defined with smaller MNPs at lower concentrations. Fluorescent signals were detected in larval digestive tracts at all except D-shaped larval stage, and on the mantle and foot in pediveligers. Therefore, MNP intake adversely affects larval physiological conditions by the synchronal effects of MNP size and concentration. Our findings highlight the implications of MNP characteristics on Pacific oyster larvae, emphasizing the interplay between size, concentration, and physiological responses, crucial for mitigating nanoparticle pollution in marine ecosystems.

Impact of numerous larval diets on the biology of pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) under laboratory conditions

BackgroundPink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) has become a potential pest of cotton by causing substantial yield losses around the world including Pakistan. Keeping in view the facts like limited research investigations, unavailability, and high cost of artificial diet’s constituents and their premixes, the present research investigations on the dietary aspect of P. gossypiella were conducted. The larvae of P. gossypiella were reared on different diets that were prepared using indigenous elements. The standard/laboratory diet comprised of wheat germ meal 34.5 g, casein 30.0 g, agar–agar 20.0 g, sucrose 10.0 g, brewer’s yeast 5.0 g, α-cellulose 1.0 g, potassium-sorbate1.5 g, niplagin 0.5 g, decavitamin 0.01 g, choline-chloride 0.06 g, maize-oil 3.30 g, honey 2.0 g, and water 730.0 mL. Alternatives to cotton bolls and wheat germ meal were okra seed sprouts, okra fruit, cottonseed meal, and okra seed meals, which were included in the study to introduce an efficient and economic mass-rearing system.ResultsThe larval development completed in 19.68 d ± 0.05 d with a weight of 20.18 mg ± 0.20 mg at the fourth instar fed on the cottonseed meal-based diet instead of wheat germ meal based diet. On the same diet, 84.00% ± 4.00%, 17.24 mg ± 0.03 mg, and 7.76 d ± 0.06 d were recorded as pupae formation, pupal weight, and pupal duration, respectively. Adult emergence, 76.00% ± 1.00% was recorded from pupae collected from larvae raised on cottonseed meal-based diet. These male and female moths lived for 40.25 d ± 0.10 d, and 44.34 d ± 0.11 d, respectively. Females deposited 21.28 ± 0.04 eggs per day with the viability of 65.78% ± 0.14%. The larval mortality at the fourth instar was 37.20% ± 1.36% and malformed pupation of 12.00% ± 1.41% was recorded. Replacement of wheat germ meal with that of local meals (cottonseed and okra seed) in the standard laboratory diet has saved 463.80 to 467.10 PKR with 1.62 to 1.63 cost economic returns, respectively.ConclusionThis research is of novel nature as it provides a concise and workable system for the economic and successful rearing of P. gossypiella under laboratory conditions.

Struggling to survive: A comparison of Vanessa cardui larval survivorship on putative host plants

AbstractThe painted lady butterfly (Vanessa cardui) is a generalist herbivore with a global distribution. In North America, over 100 species have been identified as V. cardui larval host plants. This cosmopolitan species is commercially available in all life stages and can be reared on an artificial diet. As a result, V. cardui commonly serves as a model organism for education and outreach. However, gaps in our knowledge remain with regard to V. cardui ecology and larval host plant suitability for supporting complete development of larvae to reproductive adulthood. In a laboratory setting, we tested host plant suitability of five reported host plants commonly found in California sage scrub ecosystems by assessing survival of V. cardui caterpillars in its entirety. We also assessed how commercially sourced larvae survived on artificial diet: both raising the caterpillars exclusively on artificial diet as well as switching diets from artificial to thistle (a commonly reported host plant) and switching from thistle to artificial diet. We found that all commercially sourced caterpillars exhibited both high larval mortality and low pupation rates when reared on host plants, although larvae reared on Malacothamnus fasciculatus and Sphaeralcea ambigua survived longest. Moreover, M. fasciculatus and S. ambigua were the only host plants tested that supported successful pupation. This contrasted with 63% higher survival of wild‐collected larvae. Our findings suggest that commercially obtained V. cardui may struggle to utilize wild host plants and that future investigations into host plant suitability in wild populations are needed. Additionally, future research using commercial larvae should consider the implications for interpreting host plant suitability as larvae may exhibit adaptations to artificial diet or the loss of adaptation to consuming plant material.

Anthelmintic efficacy of nitazoxanide in dogs naturally infected with Toxocara canis.

Toxocara canis (T. canis) is a gastrointestinal nematode in dogs, and its larvae also infect humans, causing severe larval migratory disease. Anthelmintic drugs have become the primary means to combat T. canis. In this study, the efficacy of nitazoxanide (NTZ) was tested against all the internal stages of T. canis, including L3 larval stage in vitro experiments and gastrointestinal worm in vivo experiments. In the in vitro experiment, after treatment with NTZ at 7.81 and 62.5 μg/mL for 12 h, the larval mortality efficacy reached 90.0 and 100.0%, respectively. In the in vivo experiments, 100 mg/kg NTZ possessed good anthelmintic efficacy against T. canis, with an egg per gram (EPG) reduction of 99.19%, and 90.00% of dogs cleared with residual worms. These results were comparable to those of the positive control drug. The highest anthelmintic efficacy was observed in the group treated with 150 mg/kg NTZ. Based on faecal egg counts, the number of T. canis eggs decreased by 100.00%, and the percentage of dogs cleared with residual worms achieved 90.00% after 7 days of treatment in the 150-mg/kg NTZ treatment group. In general, NTZ showed great potential to be applied as an anthelmintic against T. canis.

METARHIZIUM ANISOPLIAE SENSU LATO NATIVE TO LIVESTOCK SOILS CAUSES HIGH MORTALITY ON RHIPICEPHALUS MICROPLUS LARVAE, ADULTS AND AFFECTS THEIR REPRODUCTION.

The acaricidal effect of 14 strains of Metarhizium anisopliae sensu lato isolated from soil of livestock farms in the Mexican tropics was evaluated against larvae and engorged females, and during the laying and hatching of eggs of Rhipicephalus microplus (Ixodida: Ixodidae). For each fungal strain, the larvae mortality percentage was evaluated through a larval immersion test, while the reproductive efficiency indices in engorged females were measured using adult immersion tests at a dose of 1 × 108 conidia/ml. All strains of M. anisopliae (s.l.) proved to be highly effective against R. microplus larvae (66-100%) and engorged females (100%). The strains also showed a good effect in inhibiting egg laying (16.45-56.38%) and a moderate effect in decreasing egg hatching (5.24-32.68%). Two strains demonstrated to be effective against all development phases of R. microplus in an integrated manner.

Evaluation of some bio pesticidal plants in the management of Meloidogyne incognita

Utilization of compounds in extracts derived from medicinal plants is in vogue now for managing Meloidogyne incognita on crops owing to the unpopular use of synthetic nematicides especially in Sub-Saharan Africa. In this study, extracts from Azadirachta indica A. Juss and Hyptis suaveolens obtained using hexane, chloroform, ethyl acetate and methanol were tested for their efficacy in inhibiting egg hatching and inducing larval mortality of Meloidogyne incognita obtained from tomato bioassay maintained in Screenhouse. The extracts obtained from each solvent were reconstituted using Tween80+Dimethylsulfoxide (DMSO) and evaluated on hatching inhibition and larval mortality of Meloidogyne incognita at concentrations of 0.5%, 1.0%, and 1.5%. Furadan served as standard checks while distilled water and Tween80+(DMSO) as controls. Two separate experiments were conducted with 39 treatments each arranged in a Completely Randomized Design (CRD) with four repetitions on the laboratory bench for the hatching inhibition and larval mortality. Ninety (90) µL of each extract was added to 10 µL suspension containing either 15 eggs or second-stage larvae of Meloidogyne incognita pipette into cavity glass blocks. Hatching inhibition and larval mortality readings were recorded at 6, 12, 24, and 36 hours. Results indicated that Neem and Hyptis mixture at all concentrations extracted using any of the solvents gave 100% egg hatching inhibition from the 6th to the 36th h after treatment application. Only Neem and Hyptis mixture at 0.5% extracted in chloroform gave 100% larval mortality at the 6th h till the 36th h among the lowest concentration of the mixtures of the plant extracts. Combined solvent extracts of the two plants showed the highest activity in both hatching inhibition and larval mortality but individual solvent extracts showed the highest activity only at the highest rates used. The acute toxicity test of the most effective solvent extract of Neem and Hyptis at 0.5% extracted in Chloroform did not cause any sign of toxicity or death in the test animals.